Graphene has a plane monolayer structure including a 2-dimensional lattice made of carbon atoms. Graphene is a basic structural element of various allotropes of graphite having different dimensional structures. That is, the graphene may be a basic structure of fullerene (0-dimensional structure), carbon nanotube (1-dimensional structure) or graphite stacked in a 3-dimensional structure. In many of recent researches, peculiar properties of graphene, such as a zero band gap, derived from its hexagonal crystalline structure, two interpenetrating triangular subordinate lattice structures and its one-atom-size thickness are attracting attention. Further, graphene also has a peculiar electron transmission property, and, thus, it exhibits very special phenomena which have not been conventionally observed. A half-integer quantum Hall effect and a bipolar super-current transistor effect are examples of such peculiar phenomena, and these effects are also deemed to be resulted from the unique structure of graphene. Graphene oxide (GO), which is an oxidized form of graphene, is capable of quenching a fluorescence signal of organic fluorescent dyes through FRET (Fluorescence Resonance Energy Transfer), which depends on a strong bond between the graphene oxide and hydrophobic molecules and a single-strand nucleic acid through π-π stacking and/or a hydrogen bond interaction and a fluorescence quenching capability of the graphene oxide.
A method of detecting a specific nucleic acid (DNA or RNA) or protein is basically an important technique in the field of scientific research. As it becomes possible to detect and investigate a specific nucleic acid or protein, researchers can specify which genetic and biological marker is an index indicating human health condition. By using such a method of detecting a nucleic acid and a protein, gene variation of pathogen present in a sample or a specific gene expression can be observed. Further, miRNA (microRNA), which is a microscopic RNA molecule composed of about twenty (20) nucleic acids and which does not encode protein is one of important biomolecules that exist within a human body, is known to be related to various biological processes such as cell proliferation or differentiation.
PNA (Peptide Nucleic Acid) is an artificially synthesized nucleic acid. Since a backbone of oligonucleic acid is composed of peptide bonds, not phosphodiester bonds, PNA is electrically neutral while having a very strong binding force and is very stable against nuclease and proteinase. Thus, when used as a probe, PNA exhibits very high stability.
Recently, a molecular biological method or biochemical method in biology is widely employed to conduct a research on miRNA. Microarray or real-time PCR as a non-array technique are examples of the most well-known existing research methods, and various other methods are also being developed. For example, there has been reported a relevant research entitled “Bio-imaging probe for detecting intracellular molecules and treating disorders” (Korean Patent Publication No. 2011-0120749). However, these methods have drawbacks in that multiplexed-detection is impossible, a real-time detection is difficult and cost of detection is high.